IV. Stanley R. Mickelsen Safeguard Complex
B. Facility Description
4. Missiles
. . . . The Spartan was the long range interceptor, a three stage, 55 foot, solid propellant missile designed to intercept attacking ballistic missiles at long ranges outside the atmosphere. Each missile was stored in an underground silo and was guided to its target by the MSR and its data processors. Spartan was capable of maneuvering both in and out of the atmosphere. Its nuclear warhead ejected hot x-rays, deadly to nuclear-armed reentry vehicles. The third stage, which operates outside the atmosphere, could be ignited from the ground on command, entirely automated through the Safeguard data processing system or, when necessary, by manual intervention. The nuclear warhead was equipped with elaborate safety devices to preclude detonation until after it reached a safe altitude.